Excitation-Based Damping Controller Synthesis and Benchmark Verification for Mitigation of Low-Frequency Electromechanical Oscillations in DFIG-Penetrated Multi-Machine Grids

Abstract

Large-scale absorption of converter-interfaced renewable generation is reshaping the oscillatory signature of interconnected grids and is making the suppression of low-frequency electromechanical modes markedly harder across wide operating envelopes. Stabilizers of the conventional class—the classical Δω-based PSS and the IEEE MBPSS4B structure—were conceived for networks dominated by synchronous plant, and their damping authority can deteriorate once converter-coupled sources dilute effective inertia and reshape modal participation. The present study reports a robust power system stabilizer (PSS) together with a benchmark-driven verification protocol aimed at damping electromechanical oscillations in grids hosting doubly-fed induction generators (DFIGs). Controller synthesis is carried out on the Heffron–Phillips single-machine infinite-bus (SMIB) representation, after which the design is exercised on the Kundur four-machine two-area benchmark. So that the assessment is not skewed by the renewable interface itself, a DFIG plant is embedded in Area 2 at shares of 4%, 6%, 8% and 10%, and its converter-side quantities—PWM modulation index, LC filter elements and inverter PI gains—are first optimized by Particle Swarm Optimization (PSO) under an Integral of Time-weighted Absolute Error (ITAE) criterion, which curtails converter-induced oscillatory coupling and preserves dynamic feasibility of the hybrid plant. Time-domain runs in MATLAB/Simulink R2024b indicate pronounced transient gains: for the SMIB case the settling time falls to roughly 3.184 s against 6.016 s for MBPSS4B and 11.76 s for the Δω-PSS. In the multi-machine study the stabilizer tightens rotor-angle coherency and curtails inter-area swings at every penetration level examined, while a companion small-signal frequency-domain study confirms improved phase compensation and tempered resonance peaks within 0.1–10 Hz. Damping capability is therefore retained consistently as renewable share grows, strengthening the dynamic security of low-inertia networks.